The present invention relates generally to satellites, and more particularly, to a multi-band, corrugated antenna feed horn having a hexagonal aperture, and an antenna array employing multiple such feed horns arranged in a hexagonal lattice, for example, for use in a multiple beam antenna system.
The assignee of the present invention manufactures and deploys satellites that orbit the earth and which carry communication equipment, including antenna systems, and the like. The assignee of the present invention has heretofore developed a multi-band, conical corrugated horn with a smooth-wall conical transition to a circular aperture that increases the aperture efficiency of the horn. The present invention relates to hexagonal feed horn structures for use in antenna systems on satellites and other spaceborne vehicles, and provides for an improvement over this previously-developed feed horn structure.
Prior art relating to hexagonal horns addresses a circular feed end, a xe2x80x9cflaredxe2x80x9d horn portion, and a larger, hexagonal aperture end. Other prior art includes conical, corrugated horns with circular apertures.
Prior art relating to hexagonal horns includes U.S. Pat. No. 4,757,324, entitled xe2x80x9cAntenna array with hexagonal horn,xe2x80x9d which describes the use of xe2x80x9cflaredxe2x80x9d horns with a hexagonal aperture and a circular waveguide input. U.S. Pat. No. 5,113,197, entitled xe2x80x9cConformal aperture feed array for multiple beam antenna,xe2x80x9d discusses a multiple beam array antenna that is designed with an aperture shape which conforms to the particular coverage area to which the antenna is directed, e.g., circular, elliptical, or irregular in shape. The inner horns of the feed array have hexagonal aperture dimensions, while the outer perimeter of the outer horns consist of xe2x80x9carcsxe2x80x9d so that the overall feed array perimeter xe2x80x9cmatchesxe2x80x9d the shape of the coverage area. There are numerous, prior conical corrugated antenna feed horns developed by the assignee of the present invention that have the last, circular corrugated ring as the aperture (i.e., no smooth-wall conical transition to larger circular aperture).
It is an objective of the present invention to provide for a feed horn that improves the radiation pattern symmetry, low cross-polarization levels, and bandwidth of hexagonal feed horn structures. It is also an objective of the present invention to provide for a multi-band, corrugated antenna feed horn having a hexagonal aperture to improve efficiency. It is also an objective of the present invention to provide for an antenna array employing multiple hexagonal aperture feed horns.
To meet the above and other objectives, the present invention provides for feed horn apparatus comprising a multi-band, corrugated antenna feed horn that may be used in a multiple-feed antenna system. Multiple such multi-band, corrugated antenna feed horns may be arranged to form a corrugated feed horn array or cluster of feed horns arranged in a hexagonal lattice pattern.
The corrugated feed horn comprises a hexagonal aperture formed by a circular-to-hexagonal transition section, and a corrugated section disposed adjacent to the circular-to-hexagonal transition section. A tapered section is disposed adjacent to the corrugated section, and an input section having an input/output port is disposed adjacent to the tapered section.
The corrugated feed horn has desirable properties of a multi-band, conical corrugated horn, including good beam pattern symmetry, low cross-polarization, and sidelobe levels, along with an increased horn aperture area. As a result, the efficiency of the corrugated feed horn is improved by transitioning from a circular to a hexagonal aperture.